Hydropneumatic device



Nov. 23, 1943. .J. F. JOY

HY'DROPNEUMATIC DEVICE 2 Sheets-Sheet 1 Filed March 23, 1942 3,,WW h flyWW 7% MM rinse Patented Nov. 23, 1943 9 Claims.

(Granted under amended April 30, 1928; 370 0. G.

Y The invention described herein may be manufactured and used by or forthe Government for governmental purposes, without the payment to me ofany royalty thereon.

This invention pertains to a hydro-pneumatic device and moreparticularly to an equilibrator and a bellows member for use inconjunction therewith.

An object of the invention is to provide a hy dro-pneumatic spring ofthe expansion bellows t e.

jmother object of the invention is to provide an elastic bag which isadapted for use in a hydropneumatic device.

A further object of the invention is to provide a flexible extensiblebag of elastic material which collapses into a compact, substantiallysolid mass.

extended position, the bellows being illustrated in side elevation,

Figure 2 is an enlarged axial sectional view of the right hand orhydraulic end of the equilibrator shown in Fig. l,

Figure- 2a is a smilar view of the left hand end which includes the gaschamber of the device,

Figure 3 is an axial sectional view of a portion of the device in aretracted position,

Figure 4 is a transverse sectional view on the line 4-4 of Fig. 21].,

Figures 5 and 6 are respectively end and side views of one of the disksemployed in making the bellows,

Figure 7 is an end view of the opposite side of the disk of Fig. 5, I

Figure 8 is a diagrammatic axial sectional view representing the mannerin whichthe disks are assembled to form a bellows.

Figure 9 is a similar view showing the method of assembling a modifiedbellows,

Figure 10 is a perspective view, with a portion removed, of the outermetal grommet employed in the structure represented in Fig. 9, and

Figure 11 is a perspective view of the inner metal grommet used in thebellows illustrated in Fig. 9.

Referring to the drawings, a gas cylinderl is provided with an endclosure 2 having a coupling member 3 which enables the cylinder, to besecured to a device which is to be balanced. A pasthe act of March 3,1883,as

sage 4 in the closure 2 permits the admission-of gas which is retainedin the cylinderby suitable means such as a valve 5. The oppositeend ofthe cylinder is sealed by a head or closure 6 which has a threaded,centrally disposed bore 1 which supports a hollow piston rod 8v thatprojects, to the right. 8 is provided with an enlargement which forms apiston 9. Packing material I0 is confined in an annular space H on theperiphery of the pistonby suitable means such as ring l2. The right handend of piston rod 8 adjacent the piston is conditioned with a .pluralityof ports 13 which permit the circulation of fluid in .a manner whichwill be subsequently mentioned. Encompassing the piston 9 and slidablethereon inv fiuidtight relationship is a cylinder M which issealed atits right hand end by a closure 15. A coupling member 16 serves as themeans for, attachment to a device which is-to be sustained elastically.The inner end of, cylinder M is provided with a substantiallybell-shaped cap I! which is slidable on the piston rod 8 and ismaintained in fluidtight relationship therewith by a packing glandwl8-I8. A dust sleeve l9 encloses the. piston rod 8 and is detachablymounted on a skirt 20 extending from head 6. .A valve 2| in the cap I!permits the introduction of oil into the cylinder l4.

As shown in Figures 1, 2a, and 3, the open end 22 of an extensiblebellows 23 is fastened to the fixed head 6 on the gas cylinder I bymeans of a clamping ring 24, The open end 22 surrounds the bore 1 in thehead 6. Spaced set screws 25 secure the ring to the head with sufficientpressure to create a leak-proof seal. The bellows comprises a series ofinterconnected annular disks 26 of thermoreactive elastic material suchas rubber or a synthetic rubber-like product. These are bonded togetherby means of heat and pressure at alternate inner and outer edges so asto form a bladder having a plurality of convolutions 26 (Figure 1),which, when extended and viewed in axial section, appears as delineatedin Fig. 2a. The movable end 21 of the bellows is clamped between theenlarged head 28 of an elongated guide rod 29 and a disk or guide plate30 by a nut fastener 3|. The guide rod is arranged to reciprocate in thehollow piston rod 8 and is preferably provided with longitudinal flutes32 to facilitate the passage of oil into the bellows. The enlargedhead28 is also fluted and is tapered at 33 to allow it to seat in the head 6near the end of the hollow piston rod 8 when the bellows is collapsed asshown in Figure 3. The guide rod 29 promotes aligned longitudinalexpansion of the The projecting end of the piston rod which later can bedissolved in a suitable solvent bellows and increases the life of thebellows by avoiding wear due to rubbing against the inner wall 01' thecylinder.

In the ordinary use 01' the equilibrator the coupling members 3 and Itwill be connected to parts 01' the mechanism to be balanced in such away that the unbalanced weight will tend to extend the equilibrator to aposition similar to that shown in Fig. 1. Oil or similar fluid is thenintroduced into the cylinder H in a sufilcient quantity to fill allspaces inside 01' and to the right or the expansion bellows whereby thesystem is purged of imprisoned air. Gas is then introduced through thevalve linto thecylinder I in a sumcient quantity to support the weightto be baianced. In this balanced condition the mechanism can obviouslybe shifted in either direction with a minimum expenditure of energy. Asthe load is moved in a direction tending to extendthe equilibrator, oilwill be displaced through the ports l3 in the hollow piston rod toextend the bellows member 23 against the pressure or the compressed gas.

It will be obvious that the equilibrator'might also be used in anyapplication requiring a spring suspension, in which case the load shouldbe connected thereto in such a manner as 'to tend to extend theequilibrator on increase in load. In such an application a load 01 anymagnitude may beelastically suspended by the proper choice of the gaspressure in the cylinder I. In this use of the equilibrator as ahydro-pneumatic spring it may be desirable to select the size of theports l3 in the piston rod 3 so that a throttling action will occur atthese ports or orifices whereby a shock absorbing effect will result.

When the equilibrator is telescoped into its shortest length as shown inFig. 3, the bellows 23 is collapsed into a substantially solid block andis resiliently sustained in this form by the action of gas underpressure. Both gas and oil are effectively squeezed out 01 the annularinterstices between convolutions of the bladder. Since gas tends topermeate the bellows and aerate the fiuid compartment at all times,particularly when the device is in an elongated position, theopportunity to do so is materially reduced or avoided when the bellowsis collapsed. -The block-like configuration oi the bellows increasesmany times the ordinary thickness of the elastic wall through which thegas must penetrate to mix with the oil and hence a material resistanceto such infiltration is presented. The block-shape characteristic of thecollapsed bellows has an additional feature in that a high gas pressurewill not tend to invert or force the bladder through the opening in thecylinder head 6.

Figures 5-7 illustrate the type of disk employed in fabricating abellows of the character described and Fig. 8 representsdiagrammatically one manner in which a plurality 01 these disks may beassembled. In the formation of a right cylindrical bellows, thincircular disks 26 of uncured rubber having a centrally disposed aperture34 are used. The opposite faces 01' each disk are conditioned prior tostacking. Fig. 5 represents the right hand face of a disk and has anannular inner border designated generally as A which is to be bonded toa similar area on an adjoining disk. If desired, these areas may betreated with a cement to insure a bond. The outer space designated as Bwill not be bonded to the corresponding space on a contiguous disk.Hence it is conditioned with an anti-stick material which may be in theform of a thin annular disk 33 (Fig. 8)

without injuring the completed bellows. Pig. 7 illustrates the righthand side of the disk 33 and the disposition of its active andnon-active areas,

C and D, respectively. In the stacking operation,-

active border areas C of the adjoining first and second disks aresuperimposed incontiguous relationship and an anti-stick spacer 33 isinserted between these disks and against their respective D areas. Thethird disk is stacked so that its active A area adjoins thecorresponding A surface on the preceding or second disk and an antistickspacer 35 masks the inactive 13 areas. This procedure continues until astack of the desired longitudinal dimension is attained. The stack .isthen placed in a mold unit whereupon heat and pressure are applied.Rressure is exerted parallel to the axis of the bellows on the C andidle A areas to bond the laminated structure in these zones. Thisproduces a bellows oi the character illustrated in conjunction with theequilibrator. Since the anti-stick disks are unaflected by heat andpressure, they may be dissolved after the vulcanizing operation.

Figure 9 illustrates a portion of a bellows provided with annular metalreinforcements which is manufactured in a manner similar to the be]-lows previously described. A series of metal grommets 31 are arranged sothat each grommet engages the internal edges Of a pair of disks. Annularmetal grommets 38 engage the outer edge so that the disks areinterconnected as an accordion-like extensible unit. Pressure may thenbe applied to the end grommets parallel to the bellows axis to bind theassembly together in 'a fiuidtight relationship at the desired areas.This provides a sturdy bellows sinceit is less subject to tearing at thebond zones and provides an organization with a bore of small diameterwhere such is desirable.

I claim:

i. In a hydro-pneumatic device, a, chamber containing a gas, anexpansible member in the chamber in fiuidtight relationship with the gastherein, a tubular member protruding from the chamber in communicationwith one side of the expansible member, a piston on the protruding endof the tubular member and sealing the end thereof, a chamber containinga liquid recipromember, said tubular member having an orifice thereinadjacent the piston whereby liquid in the reciprocable chamber isdisplaceable in the expansible member upon movement 01' the reciprocablechamber relative to the piston.

2 In a hydro-pneumatic device, a gas cylinder, expansible means sealingthe cylinder, a tubular member protruding from the cylinder andcommunicating with one side of the expansible means, 'a piston on theprotruding end of the tubular member, a liquid cylinder slidably mountedon the piston, and an orifice whereby liquid in the last namedcylinderis displaceable in the expansible member.

3. In a hydro-pneumatic device, a cylinder containing gas, an expansiblemeans sealing one end of the cylinder, a tubular member protruding fromthe cylinder and communicating with a side oi! the expansible means, apiston on the protruding end of the tubular member, a cylindercontaining liquid reciprocably mounted about the piston and the tubularmember, said tubular member having an orifice therein adjacent thepiston, and guide means secured to the expansible means and slidable inthe tubular member.

cably mounted about the piston and the tubular 4. The structure asdescribed in claim 3 wherein the guide means secured to the expansiblemeans comprises a fluted rod having a, close sliding fit with thetubular member.

5. The structure as described in claim 3 in cluding means on thecylinders for attachment to a device to be balanced.

6. In a hydro-pneumatic device, a cylinder containing gas, an extensiblebellows secured at one end within the cylinder and sealing an endthereof, a tubular member protruding from the cylinder and communicatingwith the interior of the bellows, a piston the tubular member, acylinder containing liquid reeiprocably mounted about the piston and thetubular member, said tubular member having at least one aperture thereinclosely adjacent the piston, and a fluted guide rod secured to the freeend of the extensible bellows and slidable in the tubular member. 7

'7. In a hydro-pneumatic device, a cylinder containing a gas, a head atone end including a coupling means, a head at the opposite end thereofhaving an aperture therein, an extensible bellows in the cylindersecured at one of its ends to the head and about the aperture therein, aprojecting tubular member secured within the aperture and communicatingwith the interior of the bellows, a fluted guide rod secured to the freeend of the bellows and extending into the tubular member in slidingrelationship, a piston on the projecting end of the tubular member andsealing the end thereof, a cylinder containing a liquid reciprocablymounted about the piston and the tubular member, a head having acoupling means on one end of the cylinder, and a head including apacking gland at the other end of the cylinder fitted about the tubularmember, said tubular member having at least one orifice therein closelyadjacent the piston whereby liquid in the reciprocable cylinder isdisplaceable into the extensible bellows against the resistance of gasupon movement of the reciprocable cylinder relative to the piston.

8. In a bellows, a plurality of annular discs of elastic materialinterconnected on alternate inner and outer edges in fluid tightrelationship, said discs adapted to form a hollow, substantiallyblock-like member when collapsed and a generally thin walled bladderwhen elongated, and a rod extending centrally through the bellows andconnected to one end thereof, said rod being provided with fluidpassages.

9. A bellows as in claim 8,wherein the rod at the end of the bellows isprovided with a disc outside the bellows and of the same diameter as thebellows discs.

JOSEPH F. JOY.

